[Lewis Thomson (OP)]

Paul would like help answering the following question.

"If we find an ancient bone can we tell if it came from a carnivore or a herbivore? There are religious fanatics in the  USA who say that the animals in Noah's ark were all herbivores and that it was a world wide flood. Thank goodness Noah was able to Fed-Ex the kiwis and kangaroos back to this part of the world before they populated the Middle East. I have seen our cat eat grass, presumably when it has been feeling a bit out of sorts. How difficult would it be to turn carnivores into herbivores?"

Can you help them find answers? Leave your insights in the comments below...

[alancalverd]

Carnivores need to tear and slice their food, hence generally have large incisors, deep-rooted canine teeth, and overlapping scissor-like premolars. Herbivores tend to have relatively short incisors (if any), negligible canines (if any), and flat grinding premolars and molars.

Difficult to imagine how so many carnivores survived a universal flood, unless they suddenly evolved from herbivores in the last 6000 years. But said religious fanatics don't accept evolution.

[chiralSPO]

I would recommend not trying to use scientific evidence or logic to argue with these types of literalists. Anyone who would claim* that "the Devil put fossils into the Earth to trick people into doubting the Creation" is beyond reason.

*for a truly terrifying look at people's commitment to religious convictions in the face of all evidence: https://www.quora.com/Why-did-the-devil-plant-dinosaur-fossils-on-Earth

[evan_au]

Perhaps Zinc isotopes could be used to distinguish the diets of frozen Siberian mammoths and tar-encased dire wolves from La Brea?
See: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4870686/